DESCRIPTION (Taken directly from the application) The purpose of the Fluorescence Activated Cell Sorting (FACS)/Immunoprobe Core Facility is to: 1) provide Flow Cytometry, Cell Sorting, and related services to investigators in the Digestive Disease Center and 2) to assist center investigators in the production of monoclonal antibodies. This core is an amalgamation of the FACS and Monoclonal Antibody individual cores that were part of our previous submission. The services provided by the FACS Core are a) assistance and training in appropriate experimental design for flow cytometry and FACS experiments; b) training and special immunofluorescence staining procedures for flow cytometry; c) fully assisted sorting-FACStar; d) fully assisted analysis-FACScan, FACScalber; e) facility maintenance and trouble shooting; f) training for the applications in Flow Cytometry and individual use of the FACScan; and g) independent, unassisted use of the FACScan by trained researchers during regular hours and on evening and weekends. The Immunoprobe Core will provide the following services and materials. a) intravenous boost and spleen fusion of immunized Balb/c mice, b) maintenance and feeding fusion yield, c) assistance in screening fusion yield, d) cloning and subcloning by terminal dilution of selected monoclonals using thymocyte feeder layers or commercially available hybridoma growth supplements, e) facilities and assistance to freeze and store hybridomas of interest, f) assistance with production of immune ascites, and g) training.